Season 1 - Crimson Climax

Returning to her mother's home island after her sudden demise, Ryou feels that the answer to her mother's odd behaviour is within her mother's origins. Despite how her mother had bade her never to return to that island and to never associate herself with Hotaruko, Ryou nonetheless feels that something should be done in order to explain her mother's eccentric sexual behavior and what caused her to act so oddly. However, what Ryou never counted on was that the island contained a dark carnal cult that lured unsuspecting woman for blood sacrifice, seduced them to their highest points of ecstasy and then brutally slew them in blood as an offering to their god; Master Mizuno.